The ets-1 and ets-2 loci are transcriptionally active in humans and express a single 6.8 Kb ets-1-specific and three 4.7, 3.2 and 2.7 Kb ets-2-specific mRNAs, respectively. The c-ets-1 (P51) and the c-ets-2 (P56)-related proteins have been identified in the human cell line, Daudi, as well as COLO 320 DM, but they are expressed at extremely low levels. In order to express the ets protein in large quantities, to study the biochemical properties and also to produce ets-specific antiserum, we have constructed several expression vectors capable of producing complete v-ets and its deletion mutants and defined human c-ets-1 and c-ets-2 gene products in E. coli. The vectors with smaller inserts produced high levels of the ets products representing greater than 5% of the total bacterial proteins. In contrast, the vectors with larger inserts produced low levels representing less than 0.5% of the total protein. The bacterial ets proteins were characterized by immunoblotting on a Western blot using the ets-specific antibodies. In E. coli. the ets proteins aggregate and exist in the form of inclusion bodies and are insoluble. However, this property allowed us to purify the ets proteins to greater than 95% homogeneity by extracting the insoluble pellet with different solvents. The purified proteins were utilized to obtain the ets-1 and the ets-2-specific polyclonal and monoclonal antiserum. These polyclonal and monoclonal antibodies will be useful in identifying and studying the biochemical and biological functions of the ets.1 and the ets-2 proteins.